Radar-based ECG enables contactless monitoring of vital signs

In conventional ECG systems, electrodes and cables must be attached directly to the patient’s body. This method poses challenges for patient groups such as individuals with burns, skin allergies, infectious diseases like COVID-19, or specific psychological conditions. The contactless radar-based system offers a non-invasive alternative that increases comfort for patients and simplifies the work of nursing staff. 

The radar sensor can monitor vital signs through clothing, blankets, and even a mattress. “The radar sensor system uses the radar chips and antennas to generate electromagnetic waves that are reflected by the body. The reflected waves are modulated by the rhythmic motion of the chest wall due to respiratory and heart activity. This can be measured and analyzed using the radar sensor system to extract the vital signs,” explains Prof. Ivan Ndip, head of the RF & Smart Sensor Systems department at Fraunhofer IZM. 

These measurements allow the identification of respiratory and cardiovascular abnormalities such as stress or cardiac arrhythmias at an early stage. Once installed, the sensor can detect even the smallest movements caused by breathing and heartbeat. 

Possible areas of use include monitoring infants, burn victims, patients with sleep disorders or limited mobility, and individuals in vehicles — especially children. The system is currently undergoing clinical testing at the Medical University of Lusatia – Carl Thiem in Cottbus. The radar unit was placed in a plastic casing under a hospital bed. Its design was adjusted to account for environmental effects on antenna performance, ensuring reliable data collection. 

“The goal is to enable measurements at a greater distance from the patient and simultaneous monitoring of multiple patients in the future,” says Uwe Maaß, member of Ndip’s team. 

The key challenge in contactless ECG is the weak signal reflected by micro-movements of the chest, which can be easily distorted by environmental factors and patient motion. To address this, the 61 GHz radar antennas and front-end board were precisely engineered to maintain a high signal-to-noise ratio (SNR). 

The system was also optimized for stable performance across different manufacturing conditions. Thanks to a specialized antenna design, the radar can focus its electromagnetic waves on a narrow area of the chest. 

Initial tests of the prototype yielded promising results: “Initial measurements of test subjects lying in a supine, side or prone position went successfully,” Ndip reports. In the next phase of development, the radar system was expanded into a multi-channel version capable of contactlessly monitoring several individuals at once. 

MEDICA-tradefair.com; Source: Fraunhofer-Gesellschaft